A capacitor is composed of two layers of a material that is electrically conductive (hereinafter, electrode) brought near to one another and separated by a material that is electrically nonconductive. Suppose the capacitor is connected to a battery with a certain voltage level (hereinafter, energy level). Charges will flow from the battery to be stored in the capacitor until the capacitor exhibits the energy level of the battery. Then, suppose further that the capacitor is disconnected from the battery. The capacitor will indefinitely exhibit the energy level of the battery until the charges stored in the capacitor are removed either by design or by accident.
This ability of the capacitor to “remember” an energy level is valuable to the operation of semiconductor integrated circuits. Often, the operation of such circuits may require that data be stored and retrieved as desired. Because of its ability to remember, the capacitor is a major component of a semiconductor memory cell. One memory cell may store one bit of data. A system of memory cells is a semiconductor memory array where information can be randomly stored or retrieved from each memory cell. Such a system is also known as a random-access memory.
One type of random-access memory is dynamic random-access memory (DRAM). The charges stored in DRAM tend to leak away over a short time. It is thus necessary to periodically refresh the charges stored in the DRAM by the use of additional circuitry. Even with the refresh burden, DRAM is a popular type of memory because it can occupy a very small space on a semiconductor surface. This is desirable because of the need to maximize storage capacity on the limited surface area of an integrated circuit.
One type of capacitor that supports an increase in storage capacity uses a metal substance as a bottom electrode and an electrically nonconductive material that has a high dielectric constant. The metal substance tends to create undesired atomic diffusion in an environment with a high temperature. Such a high temperature, however, is needed to further process the electrically nonconductive material. The undesired atomic diffusion may act to degrade the electrically nonconductive material. That act compromises the ability of the capacitor to maintain the charges. This is detrimental to the storage ability of the capacitor and would render such a memory cell defective.
Thus, what is needed are systems, devices, structures, and methods to inhibit the described effect so as to enhance capacitors with a high dielectric constant in manufacturing environments exhibiting high temperatures.